There are several methods of packaging dyed yarn. Generally, the choice of packaging method depends on how the yarn was dyed, and on the intended end use of the yarn.
Package dyed yarn is prepared by winding undyed yarn into a cone form, and causing dye to penetrate the yarn under pressure. While this process may be used for dyeing yarn with reactive dyes, vat dyes, and direct dyes, it is not suitable for indigo dyes or sulfur dyes. Package dyed yarn has the advantage that cone-form yarn packages may be used for to make either woven fabrics or knitted fabrics. However, yarn which is dyed in this fashion is susceptible to undesirable shrinkage or weight loss.
Rope dyeing may be used for Indigo, sulfur and vat dyes, but not for reactive or direct dyes. Yarn is dyed in the form of a rope having many individual threads by passing the rope through from 2 to 7 dye-baths, and then oxidizing the dyed rope in air. A rope having about 320 threads is commonly used. The individual threads in the rope are separated and wound onto a beam. The threads on the beam may then be used for weaving.
Alternatively, the rope dyed threads on the beam may be transferred to cones for knitting. This is done by separating the threads on the beam into several groups of threads, and winding each group of threads onto a spool. For example, 8 spools having 40 threads each may be made from a beam carrying 320 threads. The threads on each spool are then unwound, and separated into individual threads. Each individual thread is wound onto a bobbin. The thread on a given bobbin may then be transferred to a cone. This is a time-consuming process, and the multiple transfer steps increase the possibility of thread breakage. The possibility of thread breakage also increases as the threads become finer, or as the number of threads transferred at one time increases.
The slasher process is another method for dyeing yarn. It may be used with Indigo, sulfur, vat, reactive and direct dyes. Typically, a sheet or web of substantially parallel and non-entangled warp yarns is passed through several dye baths in sheet form, washed, dried, and wound onto a beam. For reactive dyes, the sheet of warp yarns can be passed through 2 or 3 dye baths, and is then dried on hot cylinders for thermo-fixation at a temperature of 140-150.degree. C. for about a minute prior to washing. After washing, the sheet of warp yarns is wound onto a beam. For vat and Indigo dyes, the sheet of yarn passes through several dye baths. The sheet is then oxidized chemically or by passing the sheet through air, and wound onto a beam after washing and drying. The slasher process can also be used to dye yarn in sheet form with sulfur dyes or direct dyes. With the slasher process, different colors can be dyed simultaneously, as different groups of threads can be dyed in different dyebaths and then brought together on a single beam after drying. In package dyeing, only one color can be dyed at a time.
The slasher process of dyeing yarn has major advantages over the cone dyeing process. Slasher dyeing of a sheet of yarn is a continuous process, whereas cone dyeing is a batch process. Also, with the slasher process, the color of the yarn can be observed during the dyeing process, allowing color corrections to be carried out immediately. With cone dyeing, the color of the yarn is not seen until the dyeing process is complete, making color correction difficult at best.
Also, the slasher process is cheaper than the cone dyeing process, as smaller amounts of chemicals are used in dyeing the same weight of yarn. Also, cone dyeing calls for greater inputs of water and energy.
However, the slasher process as currently used has a significant disadvantage over cone dyeing and rope dyeing. Specifically, a sheet of warp yarns wound onto a beam after being dyed by the slasher process may not be conveniently used for knitting. To date, an effective method of transferring yarn dyed by the slasher process from the beam to cones for use in knitting or as filling yarns in weaving has not been developed.